DESCRIPTION: Margin discoloration is considered a sign of failure in composite resin restorations and is used as a criterion for the "decision to replace" a restoration. It is assumed that penetration of oral fluids into the debonded material/tooth interface would result in recurrent caries in three years. The primary purpose of this continuation application is to request extension of the current three year study for two additional years (years 4 and 5). The objectives of the current study are: 1) to morphologically characterize the interface of discolored margins on existing composite restorations over time using a surgical microscope and magnified digital images, 2) to assess the incidence of recurrent caries that develop over a five year period as a result of these defects and 3) to conduct a randomized, single site clinical trial to assess the outcomes of two conservative management regimens on 360 patients. The population is largely geriatric with 58% of patients over 60. In the clinical trial, an observed control group is compared to a treatment group in which the non-carious margin defect was removed and resealed, following the preventive resin/sealant model. The study unit is a composite restoration and the primary outcome variable is the presence of recurrent caries at annual recalls. Predictor factors include: morphological characteristics measured directly and on a magnified visual image (20X); established ordinal scale ratings for margin discoloration and margin adaptation; and bacteriologic assay using a needle stick sample to screen for streptococcus mutans. The incidence of recurrent caries is extremely low at three years; 3.3% for the control and 1.1% for the treatment (35%, expected). Statistical analysis of such low values is not meaningful but the results strongly support a "no treatment' decision. If recurrent caries increases over the next two years, incidence rates and odds ratios will be calculated for the disease (caries) in the control group, given the exposure (margin defec0. If caries increases for the control group only, resealing will be preferred over replacement. Two significant factors that support the proposed extension are: 1) the implication is that extending restoration survival time should conserve tooth structure and significantly decrease the costs for restoration replacements (potentially by 50% for resealing or 100% for observation) of these defects over five years in an aging population and 2) the recall rate at year three was 81%. excluding failures, and the patients are very willing to continue recall.